Apparatus for drying a product suspended in liquid



Dec. 5, 1967 A. MERCIER 3,356,223

APPARATUS FOR DRYING A PRODUCT SUSPENDED IN LIQUID Filed May 12, 1966 '7 INVENTOR.

. ANDRE MERCIER United States Patent 3,356,223 APPARATUS FOR DRYING A PRODUCT SUSPENDED IN LIQUID Andre Mercier, La Madeleine, Nord, France, assignor to Societe Fives Lille-Cail, Paris, France Filed May 12, 1966, Ser. No. 549,605 5 Claims. (Cl. 210-377) ABSTRACT OF THE DISCLOSURE In an apparatus for drying a product suspended in a liquid, a rotary drier with a liquid-permeable wall surrounding its axis of rotation. A plurality of deflectors coaxially surround the axis and have outer peripheral portions of different diameters which are progressively larger in one direction along the axis. Separate streams of the product suspended in liquid are introduced into the drier respectively into engagement with the outer peripheral portions of the deflectors.

The present invention relates to a drying apparatus, and in particular to centrifugal drying in a discontinuous manner.

In particular, the present invention relates to the charging of the interior of a drier with a product which is suspended in a liquid and which is to be dried in the drier.

One of the problems encountered in conventional centrifugal driers of this type resides in the fact that the materials introduced into the drier are not uniformly distributed therein so that the drier is unavoidably in an unbalanced condition, particularly at high rotary speeds.

It is accordingly a primary object of the present invention to provide an apparatus according to which it becomes possible to introduce materials into the drier in such a manner that the materials will be uniformly distributed in the drier so as to avoid unbalance at high speeds.

The charging of centrifugal driers is conventionally carried out by pouring into a drier, whose lower outlet has previously been closed, a given quantity of the ma terial which is to be treated in the drier, this material consisting of the product which is initially suspended in a liquid. When the rotation of the drier is started, the materials therein are projected by centrifugal force against an inner cylindrical surface of the drier and are distributed over this surface. Under equilibrium conditions at relatively low speeds, the inner surface of the material distributed along the drier wall, in the form of a layer engaging the same, has the configuration of part of a parabolic surface of revolution, and this surface of the layer of material engaging the rotary drier wall tends to become cylindrical as the rotary speed of the drier increases.

In the case where the product to be dried is suspended in a highly viscous liquid, the distribution of the material over the inner wall surface of the drier is not uniform. However, during charging of the drier, the hollow spaces or cavities defined by the non-uniform distribution of the product are filled by the liquid in which the product is suspended and, therefore, there is no apparent unbalance. However, upon passing of the mother liquor through the drier wall so that the product retained thereby is almost completely dry, the lack of uniformity in the distribution of the product produces an unbalance which brings about vibrations of the drier at high speeds.

It is therefore an object of the present invention to avoid these drawbacks, and to provide an apparatus which will reliably distribute the product which is to be dried uniformly along the inner surface of a rotary drier wall through which the mother liquor can pass while the product which is to be dried is retained by the wall at its inner surface.

In particular, in accordance with the invention, a plurality of liquid streams, with the products suspended therein, are introduced into the rotary drier in directions, respectively, which are substantially parallel to the axis of rotation of the drier, and the thus-introduced individual streams of liquid are deflected in the drier at deflection locations which are displaced with respect to each other in the direction of the drier axis, substantially radially away from this axis into engagement with the inner surface of a rotary drier wall which surrounds the drier axis and through which the liquid can pass while the product is retained thereby.

The apparatus of the invention includes a plurality of rotary deflecting means which coaxially surround and are distributed along the drier axis and which have outer peripheral deflecting portions which are of progressively greater diameters in one direction along the drier axis, the apparatus including a means for introducing separate streams of the liquid, with the product suspended therein, into engagement with these peripheral portions of the plurality of rotary deflecting means so that the peripheral deflecting portions respectively deflect the streams substantially radially away from the drier axis. The drier includes a rotary wall means which surrounds this axis and which has an inner surface against which the several streams are deflected by the plurality of rotary deflecting means, this wall means being permeable to the liquid so that it passes through the wall means while the wall means retains the product which was initially suspended in the liquid. The drier axis is preferably vertical, and the plurality of deflecting means preferably take the form of relatively flat discs which are uniformly distributed along the drier axis respectively in planes normal thereto, the separate streams preferably being introduced downwardly into the drier to engage upwardly directed surfaces of the peripheral deflecting portions. The uniform distribution of the plurality of deflecting means in the drier at dilferent elevations therein results in deflection of the several streams against substantially equal surface area portions of the inner surface of the rotary drier wall which surrounds the axis of rotation of the drier.

The invention is illustrated by way of example in the accompanying drawing in which one embodiment of an apparatus according to the invention is schematically illustrated in a fragmentary sectional elevation taken in a vertical plane which includes the drier axis.

The centrifugal drier shown in the drawing includes a rotary basket 10 having a bottom which is fixed to the lower end of a substantially vertical rotary drive shaft 12 whose axis coincides with the axis of rotation of the drier. The rotary basket 10 has a perforated cylindrical side wall which carries a drying sieve 14 whose inner surface defines the inner surface of the rotary drier wall means. The basket 10 is situated in the interior of a suitable stationary tank 16 in which the liquid phase of the materials introduced into the drier is collected.

The rotary shaft 12 driven in any suitable way, carries a plurality of deflecting means in the form of three relatively flat discs 18, 20 and 22 which are fixed to the shaft 12 for rotation therewith and which are respectively situated substantially centrally in zones 24, 26 and 28, respectively, of the rotary basket 10, so that the several discs 18, 20 and 22 are situated substantially in medial planes of the zones 24, 26 and 28. In other words, each deflecting means is situated substantially midway between the top and bottom end of the zone in which it is situated. Each of the zones 24, 26 and 28 has a volume equal to one-third of the interior volume of the basket 10. Thus, each of these zones extends through a third of the depth of the basket.

The drier is supplied from a distributor 30 by way of a supply conduit 32 which fixedly carries, at its end distant from the distributor 30, a valve 34 provided with a movable valve member 36 which is capable of opening and closing the valve and which is controlled by a pneumatic or hydraulic jack 38 in a well known manner. In its interior, just above the path along which the valve member 36 moves, the valve 34 is provided with dividing baffles or blades 49 which serve to divide the outlet of the valve 34 into three individual outlets of rectangular configuration and of equal areas, so that, by way of these baffles 40, the single common stream which is delivered to the valve 34 by the conduit 32 is divided into three separate streams of equal cross-sectional areas. The dividing blades or baffles 40 have a prismatic, substantially triangular cross sectional configuration and have upwardly directed crests, as indicated in the drawing. Thus, during operation of the apparatus, the material which is to be dried and which is in the form of a product suspended in liquid flows from the distributor 30 along the conduit 32 so as to arrive at the valve 34 where the single common stream is divided into three separate streams by the baflles 40.

As is apparent from the drawing, the several deflecting means 18, 20 and 22 are not only uniformly distributed along the interior of the basket at different elevations therein but, in addition, the plurality of deflecting means respectively have outer peripheral deflecting portions whose diameters are progressively greater in a downward direction along the axis of the drier. The location of the valve 34 and its baflles 40, which together form an introducing means for introducing the separate liquid streams into the drier through the open top of the basket 10, has with respect to the several deflecting means a relationship which will direct that stream which is nearest to the axis of the drier into engagement only with the outer peripheral deflecting portion of the disc 18, while the intermediate stream issuing from the valve 34 will engage only the upwardly directed surface of the outer peripheral deflecting portion of the intermediate disc 20. The outermost stream, which is situated most distant from the axis of the drier, flows into the drier along a path which brings this outermost stream into engagement only with the upwardly directed surface of the outer peripheral deflecting portion of the lowermost disc 22.

The several dics rotate together with the shaft 12 at a speed which is sufficiently great to provide a centrifugal deflection of the thus-introduced material substantially radially away from the axis of the drier into engagement with the inner surface of the drier wal means which surrounds the drier axis. Charging of the drier is thus brought about at three different elevations, respectively situated substantially midway between the upper and lower ends of the several zones 24, 26 and 28. There fore, as a result of these different deflection locations, the introduced streams are directed in the directions of the arrows shown in the drawing along the inner surface of the sieve 14, and any given part of any one stream is required to travel through a distance which is no greater than one-sixth of the depth of the drier 10.

Moreover, at each charging elevation, which is to say at each deflection location where a stream is deflected by one of the deflecting means, the quantity of material which must be accelerated locally up to the tangential speed of the rotary drier wall means is no greater than one-third of the total material which is introduced into the drier and, as a consequence, this acceleration of the stream is brought about with a relative slip, between the streams and the inner surface of the drier wall means, which is considerably less than if the entire amount of material were deflected at one location into engagement with the rotary drier wall.

The liquid phase of the streams filters through the sieve 14 and the perforations of the outer support wall for the sieve 14 to be collected in the tank 16 from which this liquid phase can be emptied through the tubular outlet 17.

At the end of the drying operation, the dried product, which is retained at the inner surface of the rotary wall means of the basket 10, is emptied through one or more openings 11 which are formed in the bottom wall of the rotary basket 10.

It is of course evident that a different number of deflecting discs and streams can be provided depending upon the depth of the basket 10 and the particular difficulty encountered in the introduction of the material into the drier. On the other hand, the several rotary deflecting discs 18, 20, 22 can be driven at a speed different from that of the basket 10 as, for example, by extending the drive shaft 12 through a hollow tubular drive shaft which directly carries the deflecting discs and which is driven at a speed of rotation different from the shaft 12.

Moreover, structures different from those described above, but technically equivalent, can be used for the purpose of dividing the common stream flowing along the conduit 32 into a plurality of separate streams.

What is claimed is:

1. In an apparatus for drying a product which is suspended in a liquid, a rotary drier having a predetermined axis of rotation and including wall means surrounding said axis of rotation and having an inner surface directed toward said axis of rotation, said wall means being permeable to the liquid so as to provide for passage of the liquid through the wall means and said wall means retaining said product at said inner surface after the liquid passes through said wall means, a plurality of rotary deflecting means coaxially surrounding and distributed along said axis, said plurality of deflecting means repectively having outer peripheral portions of different diameters which are progressively larger in one direction along said axis, and introducing means for introducing separate streams of said liquid, with the products suspended therein, into the drier respectively into engagement with said outer peripheral portions, said plurality of rotary deflecting means when engaged at their outer peripheral portions by said streams, respectively, defleeting said streams substantially radially away from said axis into engagement with different portions, respectively, of said inner surface of said wall means.

2. The combination of claim 1 and wherein said axis is vertical and said plurality of rotary deflecting means have their outer diameters arranged so as to be progressively larger in a downward direction, said introducing means introducing said streams downwardly into the interior of the drier into engagement with said peripheral portions, respectively, of said plurality of deflecting means, whereby said streams are deflected in substantially horizontal directions into engagement with said inner surface of said wall means.

3. The combination of claim 2 and wherein said introducing means for introducing said separate streams is in the form of a valve having in its interior dividing 5 baffles which divide a single stream received by said valve into said plurality of streams.

4. The combination of claim 2 and wherein said plurality of deflecting means are respectively in the form of substantially flat discs respectively situated in planes normal to said axis.

5. The combination of claim 2 and wherein said plurality of deflecting means are equidistantly spaced from each other along said axis and are also uniformly distributed in the interior of said drier, so that said plurality of deflecting means deflect the several streams respectively into engagement with substantially equal areas of said inner surface of said Wall means.

6 References Cited UNITED STATES PATENTS 618,814 1/1899 Darby 210377 2,796,990 6/1957 Peck 210377 3,269,028 8/ 1966 Strich 210-377 FOREIGN PATENTS 569,537 8/1958 Belgium.

656,631 2/193 8 Germany.

675,179 5/ 1939 Germany.

SAMIH N. ZAHARNA, Primary Examiner.

REUBEN FRIEDMAN, Examiner.

15 J. L. DE CESARE, Asisstant Examiner. 

1. IN AN APPARATUS FOR DRYING A PRODUCT WHICH IS SUSPENDED IN A LIQUID, A ROTARY DRIVER HAVING A PREDETERMINED AXIS OF ROTATION AND INCLUDING WALL MEANS SURROUNDING SAID AXIS OF ROTATION AND HAVING AN INNER SURFACE DIRECTED TOWARD SAID AXIS OF ROTATTION, SAID WALL MEANS BEING PERMEABLE TO THE LIQUID SO AS TO PROVIDE FOR PASSAGE OF THE LIQUID THROUGH THE WALL MEANS AND SAID WALL MEANS RETAINING SAID PRODUCT AT SAID INNER SURFACE AFTER THE LIQUID PASSES THROUGH SAID WALL MEANS, A PLURALITY OF ROTARY DEFLECTING MEANS COAXIALLY SURROUNDING AND DISTRIBUTED ALONG SAID AXIS, SAID PLURALITY OF DEFLECTING MEANS REPECTIVELY HAVING OUTER PERIPHERAL PORTIONS OF DIFFERENT DIAMETERS WHICH ARE PROGRESSIVELY LARGER IN ONE DIRECTION ALONG SAID AXIS, AND INTRODUCING MEANS FOR INTRODUCING SEPARATE STREAMS OF SAID LIQUID, WITH THE PRODUCTS SUS- 